Leukemia (leukaemia) is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called “blasts”. Leukemia is a broad term covering a spectrum of diseases. In turn, it is part of the even broader group of diseases affecting the blood, bone marrow, and lymphoid system, which are all known as hematological neoplasms.
Clinically and pathologically, leukemia is subdivided into a variety of large groups. The first division is between its acute and chronic forms. Acute leukemia is a family of serious medical conditions relating to an original diagnosis of leukemia. Forms of acute leukemia include: acute myeloid leukemia, acute erythroid leukemia, acute lymphoblastic leukemia, T-cell acute lymphoblastic leukemia, adult T-cell leukemia/lymphoma, precursor T acute lymphoblastic leukemia/lymphoma, blast crisis of chronic myelogenous leukemia. Chronic leukemia is an increase of abnormal white blood cells. It differs from acute leukemia, and is categorized as myelogenous or lymphocytic. Chronic leukemia may refer to: chronic myelogenous leukemia, chronic lymphocytic leukemia, hairy cell leukemia. Additionally, the diseases are subdivided according to which kind of blood cell is affected. This split divides leukemias into lymphoblastic or lymphocytic leukemias and myeloid or myelogenous leukemias.